DPR-A, DPR-A/E01, DPR-A/E01-B1C1
LECTROSONICS, INC.
4
Input Limiter
A DSP-controlled analog audio limiter is employed
before the analog-to-digital (A-D) converter. The limiter
has a range of more than 30 dB for excellent overload
protection. A dual release envelope makes the limiter
acoustically transparent while maintaining low distor-
tion. It can be thought of as two limiters in series, a fast
attack and release limiter followed by a slow attack and
release limiter. The limiter recovers quickly from brief
transients, with no audible side effects, and also recov-
ers slowly from sustained high levels, to keep audio dis-
tortion low and while preserving short term dynamics.
Control Panel
The control panel includes five membrane switches and
an LCD screen to adjust the operational settings. Multi-
color LEDs are used to indicate audio signal levels for
accurate gain adjustment, battery status and encryption
key function.
Alternate Recording Function
The DPR has a built in recording function for use in
situations where RF may not be possible or to work as
a stand alone recorder. The record function and trans-
mit functions are exclusive of each other - you cannot
record AND transmit at the same time. When the unit is
transmitting and recording is turned on, the audio in the
RF transmission will stop, but the battery status will still
be sent to the receiver.
The recorder samples at 48 kHz rate with a 24 bit
sample depth. The micro SDHC card also offers easy
firmware update capabilities without the need for a USB
cable or driver issues.
Encryption
When transmitting audio, there are situations where
privacy is essential, such as during professional sport-
ing events, in court rooms or private meetings. For
instances where your audio transmission needs to be
kept secure, without sacrificing audio quality, Lectroson-
ics implements AES256 encryption in our digital wire-
less microphone systems. High entropy encryption keys
are first created by a Lectrosonics receiver such as the
DSQD Receiver. The key is then synced with the DPR
via the IR port. The transmission will be encrypted and
can only be decoded if the receiver and transmitter have
matching encryption keys. If you are trying to transmit
an audio signal and keys do not match, all that will be
heard is silence.
General Technical
Description
The Lectrosonics DPR-A digital plug-On transmitter
benefits from a fourth generation design with specially
developed, high efficiency digital circuitry for extended
operating time on two AA batteries. The unique design
provides several distinct features for professional ap-
plications:
• Outstanding UHF operating range
• Superb audio quality
• On board recording
• Corrosion-resistant housing
The transmitter uses a standard 3-pin XLR input jack for
use with any microphone with a mating XLR connector.
An LCD, membrane switches and multi-color LEDs on
the control panel make input gain adjustments and fre-
quency selection quick and accurate, without having to
view the receiver. The housing is machined from a solid
aluminum block to provide a lightweight and rugged
package. A special non-corrosive finish resists salt wa-
ter exposure and perspiration in extreme environments.
The DSP controlled input limiter features a wide range
dual envelope design which cleanly limits input signal
peaks over 30 dB above full modulation. Switching power
supplies provide constant voltages to the transmitter
circuits from the beginning (3 Volts) to the end (1.7 Volts)
of battery life, and an ultra low noise input amplifier for
quiet operation.
The DPR-A has an external SMA antenna jack, which
accepts Lectrosonics steel flex wire AMM or AMJ series
antennas.
Low Frequency Roll-Off
The low frequency roll-off can be set for a 3 dB down
point at 25, 35, 50, 70, 100, 120 and 150 Hz to control
subsonic and very low frequency audio content in the
audio. The actual roll-off frequency will vary slightly de-
pending upon the low frequency response of the micro-
phone.
Excessive low frequency content can drive the trans-
mitter into limiting, or in the case of high level sound
systems, even cause damage to loudspeaker systems.
The roll-off is normally adjusted by ear while listening as
the system is operating.